third_party/blink/renderer/core/layout/ng/inline/ng_inline_items_builder_test.cc - chromium/src - Git at Google

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_items_builder.h"

 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/blink/renderer/core/layout/layout_inline.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/layout_ng_text.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_layout_test.h"
 #include "third_party/blink/renderer/core/style/computed_style.h"

 namespace blink {

 namespace {

 #define EXPECT_ITEM_OFFSET(item, type, start, end) \
   EXPECT_EQ(type, (item).Type());                  \
   EXPECT_EQ(start, (item).StartOffset());          \
   EXPECT_EQ(end, (item).EndOffset());

 class NGInlineItemsBuilderTest : public NGLayoutTest {
  protected:
   void SetUp() override {
     NGLayoutTest::SetUp();
     style_ = ComputedStyle::Create();
     style_->GetFont().Update(nullptr);
   }

   void SetWhiteSpace(EWhiteSpace whitespace) {
     style_->SetWhiteSpace(whitespace);
   }

   scoped_refptr<ComputedStyle> GetStyle(EWhiteSpace whitespace) {
     if (whitespace == EWhiteSpace::kNormal)
       return style_;
     scoped_refptr<ComputedStyle> style(ComputedStyle::Create());
     style->SetWhiteSpace(whitespace);
     return style;
   }

   struct Input {
     const String text;
     EWhiteSpace whitespace = EWhiteSpace::kNormal;
     LayoutText* layout_text = nullptr;
   };

   const String& TestAppend(Vector<Input> inputs) {
     items_.clear();
     Vector<LayoutText*> anonymous_objects;
     NGInlineItemsBuilder builder(&items_);
     for (Input& input : inputs) {
       if (!input.layout_text) {
         input.layout_text = LayoutText::CreateEmptyAnonymous(
             GetDocument(), GetStyle(input.whitespace));
         anonymous_objects.push_back(input.layout_text);
       }
       builder.Append(input.text, input.layout_text->Style(), input.layout_text);
     }
     text_ = builder.ToString();
     ValidateItems();
     CheckReuseItemsProducesSameResult(inputs);
     for (LayoutObject* anonymous_object : anonymous_objects)
       anonymous_object->Destroy();
     return text_;
   }

   const String& TestAppend(const String& input) {
     return TestAppend({Input{input}});
   }
   const String& TestAppend(const Input& input1, const Input& input2) {
     return TestAppend({input1, input2});
   }
   const String& TestAppend(const String& input1, const String& input2) {
     return TestAppend(Input{input1}, Input{input2});
   }
   const String& TestAppend(const String& input1,
                            const String& input2,
                            const String& input3) {
     return TestAppend({{input1}, {input2}, {input3}});
   }

   void ValidateItems() {
     unsigned current_offset = 0;
     for (unsigned i = 0; i < items_.size(); i++) {
       const NGInlineItem& item = items_[i];
       EXPECT_EQ(current_offset, item.StartOffset());
       EXPECT_LT(item.StartOffset(), item.EndOffset());
       current_offset = item.EndOffset();
     }
     EXPECT_EQ(current_offset, text_.length());
   }

   void CheckReuseItemsProducesSameResult(Vector<Input> inputs) {
     Vector<NGInlineItem> reuse_items;
     NGInlineItemsBuilder reuse_builder(&reuse_items);
     for (Input& input : inputs) {
       // Collect items for this LayoutObject.
       DCHECK(input.layout_text);
       Vector<NGInlineItem*> previous_items;
       for (auto& item : items_) {
         if (item.GetLayoutObject() == input.layout_text)
           previous_items.push_back(&item);
       }

       // Try to re-use previous items, or Append if it was not re-usable.
       bool reused =
           !previous_items.IsEmpty() &&
           reuse_builder.Append(text_, ToLayoutNGText(input.layout_text),
                                previous_items);
       if (!reused) {
         reuse_builder.Append(input.text, input.layout_text->Style(),
                              input.layout_text);
       }
     }

     String reuse_text = reuse_builder.ToString();
     EXPECT_EQ(text_, reuse_text);
   }

   Vector<NGInlineItem> items_;
   String text_;
   scoped_refptr<ComputedStyle> style_;
 };

 #define TestWhitespaceValue(expected_text, input, whitespace) \
   SetWhiteSpace(whitespace);                                  \
   EXPECT_EQ(expected_text, TestAppend(input)) << "white-space: " #whitespace;

 TEST_F(NGInlineItemsBuilderTest, CollapseSpaces) {
   String input("text text  text   text");
   String collapsed("text text text text");
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kNormal);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kNowrap);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kWebkitNowrap);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kPreLine);
   TestWhitespaceValue(input, input, EWhiteSpace::kPre);
   TestWhitespaceValue(input, input, EWhiteSpace::kPreWrap);
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseTabs) {
   String input("text text  text   text");
   String collapsed("text text text text");
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kNormal);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kNowrap);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kWebkitNowrap);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kPreLine);
   TestWhitespaceValue(input, input, EWhiteSpace::kPre);
   TestWhitespaceValue(input, input, EWhiteSpace::kPreWrap);
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseNewLines) {
   String input("text\ntext \n text\n\ntext");
   String collapsed("text text text text");
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kNormal);
   TestWhitespaceValue(collapsed, input, EWhiteSpace::kNowrap);
   TestWhitespaceValue("text\ntext\ntext\n\ntext", input, EWhiteSpace::kPreLine);
   TestWhitespaceValue(input, input, EWhiteSpace::kPre);
   TestWhitespaceValue(input, input, EWhiteSpace::kPreWrap);
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseNewlinesAsSpaces) {
   EXPECT_EQ("text text", TestAppend("text\ntext"));
   EXPECT_EQ("text text", TestAppend("text\n\ntext"));
   EXPECT_EQ("text text", TestAppend("text \n\n text"));
   EXPECT_EQ("text text", TestAppend("text \n \n text"));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseAcrossElements) {
   EXPECT_EQ("text text", TestAppend("text ", " text"))
       << "Spaces are collapsed even when across elements.";
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseLeadingSpaces) {
   EXPECT_EQ("text", TestAppend("  text"));
   EXPECT_EQ("text", TestAppend(" ", "text"));
   EXPECT_EQ("text", TestAppend(" ", " text"));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseTrailingSpaces) {
   EXPECT_EQ("text", TestAppend("text  "));
   EXPECT_EQ("text", TestAppend("text", " "));
   EXPECT_EQ("text", TestAppend("text ", " "));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseAllSpaces) {
   EXPECT_EQ("", TestAppend("  "));
   EXPECT_EQ("", TestAppend("  ", "  "));
   EXPECT_EQ("", TestAppend("  ", "\n"));
   EXPECT_EQ("", TestAppend("\n", "  "));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseLeadingNewlines) {
   EXPECT_EQ("text", TestAppend("\ntext"));
   EXPECT_EQ("text", TestAppend("\n\ntext"));
   EXPECT_EQ("text", TestAppend("\n", "text"));
   EXPECT_EQ("text", TestAppend("\n\n", "text"));
   EXPECT_EQ("text", TestAppend(" \n", "text"));
   EXPECT_EQ("text", TestAppend("\n", " text"));
   EXPECT_EQ("text", TestAppend("\n\n", " text"));
   EXPECT_EQ("text", TestAppend(" \n", " text"));
   EXPECT_EQ("text", TestAppend("\n", "\ntext"));
   EXPECT_EQ("text", TestAppend("\n\n", "\ntext"));
   EXPECT_EQ("text", TestAppend(" \n", "\ntext"));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseTrailingNewlines) {
   EXPECT_EQ("text", TestAppend("text\n"));
   EXPECT_EQ("text", TestAppend("text", "\n"));
   EXPECT_EQ("text", TestAppend("text\n", "\n"));
   EXPECT_EQ("text", TestAppend("text\n", " "));
   EXPECT_EQ("text", TestAppend("text ", "\n"));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseNewlineAcrossElements) {
   EXPECT_EQ("text text", TestAppend("text ", "\ntext"));
   EXPECT_EQ("text text", TestAppend("text ", "\n text"));
   EXPECT_EQ("text text", TestAppend("text", " ", "\ntext"));
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseBeforeAndAfterNewline) {
   SetWhiteSpace(EWhiteSpace::kPreLine);
   EXPECT_EQ("text\ntext", TestAppend("text  \n  text"))
       << "Spaces before and after newline are removed.";
 }

 TEST_F(NGInlineItemsBuilderTest,
        CollapsibleSpaceAfterNonCollapsibleSpaceAcrossElements) {
   EXPECT_EQ("text  text",
             TestAppend({"text ", EWhiteSpace::kPreWrap}, {" text"}))
       << "The whitespace in constructions like '<span style=\"white-space: "
          "pre-wrap\">text <span><span> text</span>' does not collapse.";
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseZeroWidthSpaces) {
   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B\ntext"))
       << "Newline is removed if the character before is ZWS.";
   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\n\u200Btext"))
       << "Newline is removed if the character after is ZWS.";
   EXPECT_EQ(String(u"text\u200B\u200Btext"),
             TestAppend(u"text\u200B\n\u200Btext"))
       << "Newline is removed if the character before/after is ZWS.";

   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\n", u"\u200Btext"))
       << "Newline is removed if the character after across elements is ZWS.";
   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B", u"\ntext"))
       << "Newline is removed if the character before is ZWS even across "
          "elements.";

   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text \n", u"\u200Btext"))
       << "Collapsible space before newline does not affect the result.";
   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B\n", u" text"))
       << "Collapsible space after newline is removed even when the "
          "newline was removed.";
   EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B ", u"\ntext"))
       << "A white space sequence containing a segment break before or after "
          "a zero width space is collapsed to a zero width space.";
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseEastAsianWidth) {
   EXPECT_EQ(String(u"\u4E00\u4E00"), TestAppend(u"\u4E00\n\u4E00"))
       << "Newline is removed when both sides are Wide.";

   EXPECT_EQ(String(u"\u4E00 A"), TestAppend(u"\u4E00\nA"))
       << "Newline is not removed when after is Narrow.";
   EXPECT_EQ(String(u"A \u4E00"), TestAppend(u"A\n\u4E00"))
       << "Newline is not removed when before is Narrow.";

   EXPECT_EQ(String(u"\u4E00\u4E00"), TestAppend(u"\u4E00\n", u"\u4E00"))
       << "Newline at the end of elements is removed when both sides are Wide.";
   EXPECT_EQ(String(u"\u4E00\u4E00"), TestAppend(u"\u4E00", u"\n\u4E00"))
       << "Newline at the beginning of elements is removed "
          "when both sides are Wide.";
 }

 TEST_F(NGInlineItemsBuilderTest, OpaqueToSpaceCollapsing) {
   NGInlineItemsBuilder builder(&items_);
   builder.Append("Hello ", style_.get());
   builder.AppendOpaque(NGInlineItem::kBidiControl,
                        kFirstStrongIsolateCharacter);
   builder.Append(" ", style_.get());
   builder.AppendOpaque(NGInlineItem::kBidiControl,
                        kFirstStrongIsolateCharacter);
   builder.Append(" World", style_.get());
   EXPECT_EQ(String(u"Hello \u2068\u2068World"), builder.ToString());
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseAroundReplacedElement) {
   NGInlineItemsBuilder builder(&items_);
   builder.Append("Hello ", style_.get());
   builder.AppendAtomicInline();
   builder.Append(" World", style_.get());
   EXPECT_EQ(String(u"Hello \uFFFC World"), builder.ToString());
 }

 TEST_F(NGInlineItemsBuilderTest, CollapseNewlineAfterObject) {
   NGInlineItemsBuilder builder(&items_);
   builder.AppendAtomicInline();
   builder.Append("\n", style_.get());
   builder.AppendAtomicInline();
   EXPECT_EQ(String(u"\uFFFC \uFFFC"), builder.ToString());
   EXPECT_EQ(3u, items_.size());
   EXPECT_EQ(nullptr, items_[0].Style());
   EXPECT_EQ(style_.get(), items_[1].Style());
   EXPECT_EQ(nullptr, items_[2].Style());
 }

 TEST_F(NGInlineItemsBuilderTest, AppendEmptyString) {
   EXPECT_EQ("", TestAppend(""));
   EXPECT_EQ(0u, items_.size());
 }

 TEST_F(NGInlineItemsBuilderTest, NewLines) {
   SetWhiteSpace(EWhiteSpace::kPre);
   EXPECT_EQ("apple\norange\ngrape\n", TestAppend("apple\norange\ngrape\n"));
   EXPECT_EQ(6u, items_.size());
   EXPECT_EQ(NGInlineItem::kText, items_[0].Type());
   EXPECT_EQ(NGInlineItem::kControl, items_[1].Type());
   EXPECT_EQ(NGInlineItem::kText, items_[2].Type());
   EXPECT_EQ(NGInlineItem::kControl, items_[3].Type());
   EXPECT_EQ(NGInlineItem::kText, items_[4].Type());
   EXPECT_EQ(NGInlineItem::kControl, items_[5].Type());
 }

 TEST_F(NGInlineItemsBuilderTest, IgnorablePre) {
   SetWhiteSpace(EWhiteSpace::kPre);
   EXPECT_EQ(
       "apple"
       "\x0c"
       "orange"
       "\n"
       "grape",
       TestAppend("apple"
                  "\x0c"
                  "orange"
                  "\n"
                  "grape"));
   EXPECT_EQ(5u, items_.size());
   EXPECT_ITEM_OFFSET(items_[0], NGInlineItem::kText, 0u, 5u);
   EXPECT_ITEM_OFFSET(items_[1], NGInlineItem::kControl, 5u, 6u);
   EXPECT_ITEM_OFFSET(items_[2], NGInlineItem::kText, 6u, 12u);
   EXPECT_ITEM_OFFSET(items_[3], NGInlineItem::kControl, 12u, 13u);
   EXPECT_ITEM_OFFSET(items_[4], NGInlineItem::kText, 13u, 18u);
 }

 TEST_F(NGInlineItemsBuilderTest, Empty) {
   Vector<NGInlineItem> items;
   NGInlineItemsBuilder builder(&items);
   scoped_refptr<ComputedStyle> block_style(ComputedStyle::Create());
   builder.EnterBlock(block_style.get());
   builder.ExitBlock();

   EXPECT_EQ("", builder.ToString());
 }

 class CollapsibleSpaceTest : public NGInlineItemsBuilderTest,
                              public testing::WithParamInterface<UChar> {};

 INSTANTIATE_TEST_CASE_P(NGInlineItemsBuilderTest,
                         CollapsibleSpaceTest,
                         testing::Values(kSpaceCharacter,
                                         kTabulationCharacter,
                                         kNewlineCharacter));

 TEST_P(CollapsibleSpaceTest, CollapsedSpaceAfterNoWrap) {
   UChar space = GetParam();
   EXPECT_EQ(
       String("nowrap "
              u"\u200B"
              "wrap"),
       TestAppend({String("nowrap") + space, EWhiteSpace::kNowrap}, {" wrap"}));
 }

 TEST_F(NGInlineItemsBuilderTest, GenerateBreakOpportunityAfterLeadingSpaces) {
   EXPECT_EQ(String(" "
                    u"\u200B"
                    "a"),
             TestAppend({{" a", EWhiteSpace::kPreWrap}}));
   EXPECT_EQ(String("  "
                    u"\u200B"
                    "a"),
             TestAppend({{"  a", EWhiteSpace::kPreWrap}}));
 }

 TEST_F(NGInlineItemsBuilderTest, BidiBlockOverride) {
   Vector<NGInlineItem> items;
   NGInlineItemsBuilder builder(&items);
   scoped_refptr<ComputedStyle> block_style(ComputedStyle::Create());
   block_style->SetUnicodeBidi(UnicodeBidi::kBidiOverride);
   block_style->SetDirection(TextDirection::kRtl);
   builder.EnterBlock(block_style.get());
   builder.Append("Hello", style_.get());
   builder.ExitBlock();

   // Expected control characters as defined in:
   // https://drafts.csswg.org/css-writing-modes-3/#bidi-control-codes-injection-table
   EXPECT_EQ(String(u"\u202E"
                    u"Hello"
                    u"\u202C"),
             builder.ToString());
 }

 static std::unique_ptr<LayoutInline> CreateLayoutInline(
     void (*initialize_style)(ComputedStyle*)) {
   scoped_refptr<ComputedStyle> style(ComputedStyle::Create());
   initialize_style(style.get());
   std::unique_ptr<LayoutInline> node = std::make_unique<LayoutInline>(nullptr);
   node->SetStyleInternal(std::move(style));
   return node;
 }

 TEST_F(NGInlineItemsBuilderTest, BidiIsolate) {
   Vector<NGInlineItem> items;
   NGInlineItemsBuilder builder(&items);
   builder.Append("Hello ", style_.get());
   std::unique_ptr<LayoutInline> isolate_rtl(
       CreateLayoutInline([](ComputedStyle* style) {
         style->SetUnicodeBidi(UnicodeBidi::kIsolate);
         style->SetDirection(TextDirection::kRtl);
       }));
   builder.EnterInline(isolate_rtl.get());
   builder.Append(u"\u05E2\u05D1\u05E8\u05D9\u05EA", style_.get());
   builder.ExitInline(isolate_rtl.get());
   builder.Append(" World", style_.get());

   // Expected control characters as defined in:
   // https://drafts.csswg.org/css-writing-modes-3/#bidi-control-codes-injection-table
   EXPECT_EQ(String(u"Hello "
                    u"\u2067"
                    u"\u05E2\u05D1\u05E8\u05D9\u05EA"
                    u"\u2069"
                    u" World"),
             builder.ToString());
 }

 TEST_F(NGInlineItemsBuilderTest, BidiIsolateOverride) {
   Vector<NGInlineItem> items;
   NGInlineItemsBuilder builder(&items);
   builder.Append("Hello ", style_.get());
   std::unique_ptr<LayoutInline> isolate_override_rtl(
       CreateLayoutInline([](ComputedStyle* style) {
         style->SetUnicodeBidi(UnicodeBidi::kIsolateOverride);
         style->SetDirection(TextDirection::kRtl);
       }));
   builder.EnterInline(isolate_override_rtl.get());
   builder.Append(u"\u05E2\u05D1\u05E8\u05D9\u05EA", style_.get());
   builder.ExitInline(isolate_override_rtl.get());
   builder.Append(" World", style_.get());

   // Expected control characters as defined in:
   // https://drafts.csswg.org/css-writing-modes-3/#bidi-control-codes-injection-table
   EXPECT_EQ(String(u"Hello "
                    u"\u2068\u202E"
                    u"\u05E2\u05D1\u05E8\u05D9\u05EA"
                    u"\u202C\u2069"
                    u" World"),
             builder.ToString());
 }

 }  // namespace

 }  // namespace blink
	// Copyright 2016 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_items_builder.h"

	#include "testing/gtest/include/gtest/gtest.h"
	#include "third_party/blink/renderer/core/layout/layout_inline.h"
	#include "third_party/blink/renderer/core/layout/ng/inline/layout_ng_text.h"
	#include "third_party/blink/renderer/core/layout/ng/ng_layout_test.h"
	#include "third_party/blink/renderer/core/style/computed_style.h"

	namespace blink {

	namespace {

	#define EXPECT_ITEM_OFFSET(item, type, start, end) \
	EXPECT_EQ(type, (item).Type()); \
	EXPECT_EQ(start, (item).StartOffset()); \
	EXPECT_EQ(end, (item).EndOffset());

	class NGInlineItemsBuilderTest : public NGLayoutTest {
	protected:
	void SetUp() override {
	NGLayoutTest::SetUp();
	style_ = ComputedStyle::Create();
	style_->GetFont().Update(nullptr);
	}

	void SetWhiteSpace(EWhiteSpace whitespace) {
	style_->SetWhiteSpace(whitespace);
	}

	scoped_refptr<ComputedStyle> GetStyle(EWhiteSpace whitespace) {
	if (whitespace == EWhiteSpace::kNormal)
	return style_;
	scoped_refptr<ComputedStyle> style(ComputedStyle::Create());
	style->SetWhiteSpace(whitespace);
	return style;
	}

	struct Input {
	const String text;
	EWhiteSpace whitespace = EWhiteSpace::kNormal;
	LayoutText* layout_text = nullptr;
	};

	const String& TestAppend(Vector<Input> inputs) {
	items_.clear();
	Vector<LayoutText*> anonymous_objects;
	NGInlineItemsBuilder builder(&items_);
	for (Input& input : inputs) {
	if (!input.layout_text) {
	input.layout_text = LayoutText::CreateEmptyAnonymous(
	GetDocument(), GetStyle(input.whitespace));
	anonymous_objects.push_back(input.layout_text);
	}
	builder.Append(input.text, input.layout_text->Style(), input.layout_text);
	}
	text_ = builder.ToString();
	ValidateItems();
	CheckReuseItemsProducesSameResult(inputs);
	for (LayoutObject* anonymous_object : anonymous_objects)
	anonymous_object->Destroy();
	return text_;
	}

	const String& TestAppend(const String& input) {
	return TestAppend({Input{input}});
	}
	const String& TestAppend(const Input& input1, const Input& input2) {
	return TestAppend({input1, input2});
	}
	const String& TestAppend(const String& input1, const String& input2) {
	return TestAppend(Input{input1}, Input{input2});
	}
	const String& TestAppend(const String& input1,
	const String& input2,
	const String& input3) {
	return TestAppend({{input1}, {input2}, {input3}});
	}

	void ValidateItems() {
	unsigned current_offset = 0;
	for (unsigned i = 0; i < items_.size(); i++) {
	const NGInlineItem& item = items_[i];
	EXPECT_EQ(current_offset, item.StartOffset());
	EXPECT_LT(item.StartOffset(), item.EndOffset());
	current_offset = item.EndOffset();
	}
	EXPECT_EQ(current_offset, text_.length());
	}

	void CheckReuseItemsProducesSameResult(Vector<Input> inputs) {
	Vector<NGInlineItem> reuse_items;
	NGInlineItemsBuilder reuse_builder(&reuse_items);
	for (Input& input : inputs) {
	// Collect items for this LayoutObject.
	DCHECK(input.layout_text);
	Vector<NGInlineItem*> previous_items;
	for (auto& item : items_) {
	if (item.GetLayoutObject() == input.layout_text)
	previous_items.push_back(&item);
	}

	// Try to re-use previous items, or Append if it was not re-usable.
	bool reused =
	!previous_items.IsEmpty() &&
	reuse_builder.Append(text_, ToLayoutNGText(input.layout_text),
	previous_items);
	if (!reused) {
	reuse_builder.Append(input.text, input.layout_text->Style(),
	input.layout_text);
	}
	}

	String reuse_text = reuse_builder.ToString();
	EXPECT_EQ(text_, reuse_text);
	}

	Vector<NGInlineItem> items_;
	String text_;
	scoped_refptr<ComputedStyle> style_;
	};

	#define TestWhitespaceValue(expected_text, input, whitespace) \
	SetWhiteSpace(whitespace); \
	EXPECT_EQ(expected_text, TestAppend(input)) << "white-space: " #whitespace;

	TEST_F(NGInlineItemsBuilderTest, CollapseSpaces) {
	String input("text text text text");
	String collapsed("text text text text");
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kNormal);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kNowrap);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kWebkitNowrap);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kPreLine);
	TestWhitespaceValue(input, input, EWhiteSpace::kPre);
	TestWhitespaceValue(input, input, EWhiteSpace::kPreWrap);
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseTabs) {
	String input("text text text text");
	String collapsed("text text text text");
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kNormal);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kNowrap);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kWebkitNowrap);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kPreLine);
	TestWhitespaceValue(input, input, EWhiteSpace::kPre);
	TestWhitespaceValue(input, input, EWhiteSpace::kPreWrap);
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseNewLines) {
	String input("text\ntext \n text\n\ntext");
	String collapsed("text text text text");
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kNormal);
	TestWhitespaceValue(collapsed, input, EWhiteSpace::kNowrap);
	TestWhitespaceValue("text\ntext\ntext\n\ntext", input, EWhiteSpace::kPreLine);
	TestWhitespaceValue(input, input, EWhiteSpace::kPre);
	TestWhitespaceValue(input, input, EWhiteSpace::kPreWrap);
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseNewlinesAsSpaces) {
	EXPECT_EQ("text text", TestAppend("text\ntext"));
	EXPECT_EQ("text text", TestAppend("text\n\ntext"));
	EXPECT_EQ("text text", TestAppend("text \n\n text"));
	EXPECT_EQ("text text", TestAppend("text \n \n text"));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseAcrossElements) {
	EXPECT_EQ("text text", TestAppend("text ", " text"))
	<< "Spaces are collapsed even when across elements.";
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseLeadingSpaces) {
	EXPECT_EQ("text", TestAppend(" text"));
	EXPECT_EQ("text", TestAppend(" ", "text"));
	EXPECT_EQ("text", TestAppend(" ", " text"));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseTrailingSpaces) {
	EXPECT_EQ("text", TestAppend("text "));
	EXPECT_EQ("text", TestAppend("text", " "));
	EXPECT_EQ("text", TestAppend("text ", " "));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseAllSpaces) {
	EXPECT_EQ("", TestAppend(" "));
	EXPECT_EQ("", TestAppend(" ", " "));
	EXPECT_EQ("", TestAppend(" ", "\n"));
	EXPECT_EQ("", TestAppend("\n", " "));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseLeadingNewlines) {
	EXPECT_EQ("text", TestAppend("\ntext"));
	EXPECT_EQ("text", TestAppend("\n\ntext"));
	EXPECT_EQ("text", TestAppend("\n", "text"));
	EXPECT_EQ("text", TestAppend("\n\n", "text"));
	EXPECT_EQ("text", TestAppend(" \n", "text"));
	EXPECT_EQ("text", TestAppend("\n", " text"));
	EXPECT_EQ("text", TestAppend("\n\n", " text"));
	EXPECT_EQ("text", TestAppend(" \n", " text"));
	EXPECT_EQ("text", TestAppend("\n", "\ntext"));
	EXPECT_EQ("text", TestAppend("\n\n", "\ntext"));
	EXPECT_EQ("text", TestAppend(" \n", "\ntext"));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseTrailingNewlines) {
	EXPECT_EQ("text", TestAppend("text\n"));
	EXPECT_EQ("text", TestAppend("text", "\n"));
	EXPECT_EQ("text", TestAppend("text\n", "\n"));
	EXPECT_EQ("text", TestAppend("text\n", " "));
	EXPECT_EQ("text", TestAppend("text ", "\n"));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseNewlineAcrossElements) {
	EXPECT_EQ("text text", TestAppend("text ", "\ntext"));
	EXPECT_EQ("text text", TestAppend("text ", "\n text"));
	EXPECT_EQ("text text", TestAppend("text", " ", "\ntext"));
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseBeforeAndAfterNewline) {
	SetWhiteSpace(EWhiteSpace::kPreLine);
	EXPECT_EQ("text\ntext", TestAppend("text \n text"))
	<< "Spaces before and after newline are removed.";
	}

	TEST_F(NGInlineItemsBuilderTest,
	CollapsibleSpaceAfterNonCollapsibleSpaceAcrossElements) {
	EXPECT_EQ("text text",
	TestAppend({"text ", EWhiteSpace::kPreWrap}, {" text"}))
	<< "The whitespace in constructions like '<span style=\"white-space: "
	"pre-wrap\">text <span><span> text</span>' does not collapse.";
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseZeroWidthSpaces) {
	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B\ntext"))
	<< "Newline is removed if the character before is ZWS.";
	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\n\u200Btext"))
	<< "Newline is removed if the character after is ZWS.";
	EXPECT_EQ(String(u"text\u200B\u200Btext"),
	TestAppend(u"text\u200B\n\u200Btext"))
	<< "Newline is removed if the character before/after is ZWS.";

	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\n", u"\u200Btext"))
	<< "Newline is removed if the character after across elements is ZWS.";
	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B", u"\ntext"))
	<< "Newline is removed if the character before is ZWS even across "
	"elements.";

	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text \n", u"\u200Btext"))
	<< "Collapsible space before newline does not affect the result.";
	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B\n", u" text"))
	<< "Collapsible space after newline is removed even when the "
	"newline was removed.";
	EXPECT_EQ(String(u"text\u200Btext"), TestAppend(u"text\u200B ", u"\ntext"))
	<< "A white space sequence containing a segment break before or after "
	"a zero width space is collapsed to a zero width space.";
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseEastAsianWidth) {
	EXPECT_EQ(String(u"\u4E00\u4E00"), TestAppend(u"\u4E00\n\u4E00"))
	<< "Newline is removed when both sides are Wide.";

	EXPECT_EQ(String(u"\u4E00 A"), TestAppend(u"\u4E00\nA"))
	<< "Newline is not removed when after is Narrow.";
	EXPECT_EQ(String(u"A \u4E00"), TestAppend(u"A\n\u4E00"))
	<< "Newline is not removed when before is Narrow.";

	EXPECT_EQ(String(u"\u4E00\u4E00"), TestAppend(u"\u4E00\n", u"\u4E00"))
	<< "Newline at the end of elements is removed when both sides are Wide.";
	EXPECT_EQ(String(u"\u4E00\u4E00"), TestAppend(u"\u4E00", u"\n\u4E00"))
	<< "Newline at the beginning of elements is removed "
	"when both sides are Wide.";
	}

	TEST_F(NGInlineItemsBuilderTest, OpaqueToSpaceCollapsing) {
	NGInlineItemsBuilder builder(&items_);
	builder.Append("Hello ", style_.get());
	builder.AppendOpaque(NGInlineItem::kBidiControl,
	kFirstStrongIsolateCharacter);
	builder.Append(" ", style_.get());
	builder.AppendOpaque(NGInlineItem::kBidiControl,
	kFirstStrongIsolateCharacter);
	builder.Append(" World", style_.get());
	EXPECT_EQ(String(u"Hello \u2068\u2068World"), builder.ToString());
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseAroundReplacedElement) {
	NGInlineItemsBuilder builder(&items_);
	builder.Append("Hello ", style_.get());
	builder.AppendAtomicInline();
	builder.Append(" World", style_.get());
	EXPECT_EQ(String(u"Hello \uFFFC World"), builder.ToString());
	}

	TEST_F(NGInlineItemsBuilderTest, CollapseNewlineAfterObject) {
	NGInlineItemsBuilder builder(&items_);
	builder.AppendAtomicInline();
	builder.Append("\n", style_.get());
	builder.AppendAtomicInline();
	EXPECT_EQ(String(u"\uFFFC \uFFFC"), builder.ToString());
	EXPECT_EQ(3u, items_.size());
	EXPECT_EQ(nullptr, items_[0].Style());
	EXPECT_EQ(style_.get(), items_[1].Style());
	EXPECT_EQ(nullptr, items_[2].Style());
	}

	TEST_F(NGInlineItemsBuilderTest, AppendEmptyString) {
	EXPECT_EQ("", TestAppend(""));
	EXPECT_EQ(0u, items_.size());
	}

	TEST_F(NGInlineItemsBuilderTest, NewLines) {
	SetWhiteSpace(EWhiteSpace::kPre);
	EXPECT_EQ("apple\norange\ngrape\n", TestAppend("apple\norange\ngrape\n"));
	EXPECT_EQ(6u, items_.size());
	EXPECT_EQ(NGInlineItem::kText, items_[0].Type());
	EXPECT_EQ(NGInlineItem::kControl, items_[1].Type());
	EXPECT_EQ(NGInlineItem::kText, items_[2].Type());
	EXPECT_EQ(NGInlineItem::kControl, items_[3].Type());
	EXPECT_EQ(NGInlineItem::kText, items_[4].Type());
	EXPECT_EQ(NGInlineItem::kControl, items_[5].Type());
	}

	TEST_F(NGInlineItemsBuilderTest, IgnorablePre) {
	SetWhiteSpace(EWhiteSpace::kPre);
	EXPECT_EQ(
	"apple"
	"\x0c"
	"orange"
	"\n"
	"grape",
	TestAppend("apple"
	"\x0c"
	"orange"
	"\n"
	"grape"));
	EXPECT_EQ(5u, items_.size());
	EXPECT_ITEM_OFFSET(items_[0], NGInlineItem::kText, 0u, 5u);
	EXPECT_ITEM_OFFSET(items_[1], NGInlineItem::kControl, 5u, 6u);
	EXPECT_ITEM_OFFSET(items_[2], NGInlineItem::kText, 6u, 12u);
	EXPECT_ITEM_OFFSET(items_[3], NGInlineItem::kControl, 12u, 13u);
	EXPECT_ITEM_OFFSET(items_[4], NGInlineItem::kText, 13u, 18u);
	}

	TEST_F(NGInlineItemsBuilderTest, Empty) {
	Vector<NGInlineItem> items;
	NGInlineItemsBuilder builder(&items);
	scoped_refptr<ComputedStyle> block_style(ComputedStyle::Create());
	builder.EnterBlock(block_style.get());
	builder.ExitBlock();

	EXPECT_EQ("", builder.ToString());
	}

	class CollapsibleSpaceTest : public NGInlineItemsBuilderTest,
	public testing::WithParamInterface<UChar> {};

	INSTANTIATE_TEST_CASE_P(NGInlineItemsBuilderTest,
	CollapsibleSpaceTest,
	testing::Values(kSpaceCharacter,
	kTabulationCharacter,
	kNewlineCharacter));

	TEST_P(CollapsibleSpaceTest, CollapsedSpaceAfterNoWrap) {
	UChar space = GetParam();
	EXPECT_EQ(
	String("nowrap "
	u"\u200B"
	"wrap"),
	TestAppend({String("nowrap") + space, EWhiteSpace::kNowrap}, {" wrap"}));
	}

	TEST_F(NGInlineItemsBuilderTest, GenerateBreakOpportunityAfterLeadingSpaces) {
	EXPECT_EQ(String(" "
	u"\u200B"
	"a"),
	TestAppend({{" a", EWhiteSpace::kPreWrap}}));
	EXPECT_EQ(String(" "
	u"\u200B"
	"a"),
	TestAppend({{" a", EWhiteSpace::kPreWrap}}));
	}

	TEST_F(NGInlineItemsBuilderTest, BidiBlockOverride) {
	Vector<NGInlineItem> items;
	NGInlineItemsBuilder builder(&items);
	scoped_refptr<ComputedStyle> block_style(ComputedStyle::Create());
	block_style->SetUnicodeBidi(UnicodeBidi::kBidiOverride);
	block_style->SetDirection(TextDirection::kRtl);
	builder.EnterBlock(block_style.get());
	builder.Append("Hello", style_.get());
	builder.ExitBlock();

	// Expected control characters as defined in:
	// https://drafts.csswg.org/css-writing-modes-3/#bidi-control-codes-injection-table
	EXPECT_EQ(String(u"\u202E"
	u"Hello"
	u"\u202C"),
	builder.ToString());
	}

	static std::unique_ptr<LayoutInline> CreateLayoutInline(
	void (initialize_style)(ComputedStyle)) {
	scoped_refptr<ComputedStyle> style(ComputedStyle::Create());
	initialize_style(style.get());
	std::unique_ptr<LayoutInline> node = std::make_unique<LayoutInline>(nullptr);
	node->SetStyleInternal(std::move(style));
	return node;
	}

	TEST_F(NGInlineItemsBuilderTest, BidiIsolate) {
	Vector<NGInlineItem> items;
	NGInlineItemsBuilder builder(&items);
	builder.Append("Hello ", style_.get());
	std::unique_ptr<LayoutInline> isolate_rtl(
	CreateLayoutInline([](ComputedStyle* style) {
	style->SetUnicodeBidi(UnicodeBidi::kIsolate);
	style->SetDirection(TextDirection::kRtl);
	}));
	builder.EnterInline(isolate_rtl.get());
	builder.Append(u"\u05E2\u05D1\u05E8\u05D9\u05EA", style_.get());
	builder.ExitInline(isolate_rtl.get());
	builder.Append(" World", style_.get());

	// Expected control characters as defined in:
	// https://drafts.csswg.org/css-writing-modes-3/#bidi-control-codes-injection-table
	EXPECT_EQ(String(u"Hello "
	u"\u2067"
	u"\u05E2\u05D1\u05E8\u05D9\u05EA"
	u"\u2069"
	u" World"),
	builder.ToString());
	}

	TEST_F(NGInlineItemsBuilderTest, BidiIsolateOverride) {
	Vector<NGInlineItem> items;
	NGInlineItemsBuilder builder(&items);
	builder.Append("Hello ", style_.get());
	std::unique_ptr<LayoutInline> isolate_override_rtl(
	CreateLayoutInline([](ComputedStyle* style) {
	style->SetUnicodeBidi(UnicodeBidi::kIsolateOverride);
	style->SetDirection(TextDirection::kRtl);
	}));
	builder.EnterInline(isolate_override_rtl.get());
	builder.Append(u"\u05E2\u05D1\u05E8\u05D9\u05EA", style_.get());
	builder.ExitInline(isolate_override_rtl.get());
	builder.Append(" World", style_.get());

	// Expected control characters as defined in:
	// https://drafts.csswg.org/css-writing-modes-3/#bidi-control-codes-injection-table
	EXPECT_EQ(String(u"Hello "
	u"\u2068\u202E"
	u"\u05E2\u05D1\u05E8\u05D9\u05EA"
	u"\u202C\u2069"
	u" World"),
	builder.ToString());
	}

	} // namespace

	} // namespace blink